Semiconductor memory device and manufacturing method thereof

ABSTRACT

A semiconductor memory device and a manufacturing method thereof are provided. At least one bit line structure including a first metal layer, a bit line capping layer, and a first silicon layer located between the first metal layer and the bit line capping layer is formed on a semiconductor substrate. A bit line contact opening penetrating the bit line capping layer is formed for exposing a part of the first silicon layer. A first metal silicide layer is formed on the first silicon layer exposed by the bit line contact opening. A bit line contact structure is formed in the bit line contact opening and contacts the first metal silicide layer for being electrically connected to the bit line structure. The first silicon layer in the bit line structure may be used to protect the first metal layer from being damaged by the process of forming the metal silicide layer.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a semiconductor memory device and amanufacturing method thereof, and more particularly, to a semiconductormemory device having a bit line structure and a manufacturing methodthereof.

2. Description of the Prior Art

Dynamic random access memory (DRAM) is a kind of volatile storage devicewhich is an indispensable key part of many electronic products. DRAMincludes a great number of memory cells arranged for forming an arrayconfigured to store data. Each of the memory cells may be composed of ametal oxide semiconductor (MOS) transistor and a capacitor connected inseries.

The MOS transistors of the memory cells may have different structuraldesign because of the product specification and/or the memory celldensity requirements. Therefore, the structure of the MOS transistor ofthe memory cell may be different from that of transistors on otherregions within the same chip, and the manufacturing process will becomemore complicated. Accordingly, it is very important for the relatedfield to effectively integrate the manufacturing process of the MOStransistors in the memory cell and the manufacturing process of thetransistors in other regions.

SUMMARY OF THE INVENTION

The present invention provides a semiconductor memory device and amanufacturing method thereof, a first silicon layer is formed between afirst metal layer and a bit line capping layer of a bit line structure,and the first silicon layer is used to protect the first metal layerfrom being damaged by the process of forming a metal silicide layer.

An embodiment of the present invention provides a manufacturing methodof a semiconductor memory device, including the following steps. First,a semiconductor substrate is provided. At least one bit line structureis formed on the semiconductor substrate. The bit line structureincludes a first metal layer, a bit line capping layer, and a firstsilicon layer. The bit line capping layer is disposed on the first metallayer, and the first silicon layer is disposed between the first metallayer and the bit line capping layer. At least one bit line contactopening is formed, and the bit line contact opening penetrates the bitline capping layer and exposes at least a portion of the first siliconlayer. A first metal silicide layer is formed on the portion of thefirst silicon layer exposed by the bit line contact opening. A bit linecontact structure is formed in the bit line contact opening, and the bitline contact structure contacts the first metal silicide layer for beingelectrically connected to the bit line structure.

An embodiment of the present invention provides a semiconductor memorydevice including a semiconductor substrate, at least one bit linestructure, at least one bit line contact opening, a first metal silicidelayer and a bit line contact structure. The bit line structure isdisposed on the semiconductor substrate, and the bit line structureincludes a first metal layer, a bit line capping layer, and a firstsilicon layer. The bit line capping layer is disposed on the first metallayer, and the first silicon layer is disposed between the first metallayer and the bit line capping layer. The bit line contact openingpenetrates the bit line capping layer, the first metal silicide layer isdisposed on the first silicon layer corresponding to the bit linecontact opening, and the bit line contact opening exposes at least aportion of the first metal silicide layer. The bit line contactstructure is disposed in the bit line contact opening, and the bit linecontact structure contacts the first metal silicide layer for beingelectrically connected to the bit line structure.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-11 are schematic diagrams illustrating a manufacturing method ofa semiconductor memory device according to an embodiment of the presentinvention, wherein:

FIG. 2 is a schematic drawing illustrating a fabricating stagesubsequent to FIG. 1;

FIG. 3 is a schematic drawing illustrating a fabricating stagesubsequent to FIG. 2;

FIG. 4 is a schematic drawing illustrating a storage node contact in thefabricating stage of FIG. 3;

FIG. 5 is a schematic drawing illustrating a fabricating stagesubsequent to FIG. 3;

FIG. 6 is a schematic drawing illustrating a fabricating stagesubsequent to FIG. 5;

FIG. 7 is a schematic drawing illustrating the storage node contact inthe fabricating stage of FIG. 6;

FIG. 8 is a schematic drawing illustrating a fabricating stagesubsequent to FIG. 6;

FIG. 9 is a schematic drawing illustrating the storage node contact inthe fabricating stage of FIG. 8;

FIG. 10 is a schematic drawing illustrating a fabricating stagesubsequent to FIG. 8; and

FIG. 11 is a schematic drawing illustrating the storage node contact inthe fabricating stage of FIG. 10.

DETAILED DESCRIPTION

Please refer to FIGS. 1-11. FIGS. 1-11 are schematic diagramsillustrating a manufacturing method of a semiconductor memory deviceaccording to an embodiment of the present invention. This embodimentprovides a manufacturing method of a semiconductor memory device,including the following steps. First, as shown in FIG. 1, asemiconductor substrate 10 is provided, and a memory cell region R1 anda peripheral region R2 can be defined on the semiconductor substrate 10.The memory cell region R1 is used for forming a plurality of memorycells therein, and the peripheral region R2 is used for forming devicesother than the memory cells, such as transistors that can control thesignal transmitting of word lines and/or bit lines, but not limitedthereto. The semiconductor substrate 10 may include a silicon substrate,an epitaxial silicon substrate, a silicon germanium substrate, a siliconcarbide substrate or a silicon-on-insulator (SOI) substrate, but notlimited thereto. In this embodiment, a shallow trench isolation 11 maybe formed in the memory cell region R1 of the semiconductor substrate 10for defining a plurality of active regions 13 in the memory cell regionR1 of the semiconductor substrate 10. The memory cell region R1 and theperipheral region R2 can be isolated from each other by forming a trenchisolation 12 therebetween in the semiconductor substrate 10. The shallowtrench isolation 11 and the trench isolation 12 may be formed by usingetching method to form a plurality of trenches in the semiconductorsubstrate 10 and followed by filling the trenches with an insulationmaterial, such as silicon oxide, but not limited thereto. In someembodiments, the shallow trench isolation 11 and the trench isolation 12may be formed by other suitable methods based on other considerations.Furthermore, a plurality of word lines 22 may be formed in the memorycell region R1 of the semiconductor substrate 10, and each word line 22of this embodiment may be a buried word line, but not limited thereto.The word lines 22 may be formed in the semiconductor substrate 10 andthe shallow trench isolation 11 by using burying method. A word linedielectric layer 21 may be formed between each word line 22 and thesemiconductor substrate 10, and a word line capping layer 23 may beformed on each word line 22 to cover each word line 22. The abovementioned word line dielectric layer 21, word lines 22 and word linecapping layer 23 may be formed through forming a plurality of trenchesin the semiconductor substrate 10 and the shallow trench isolation 11first and then sequentially forming the word line dielectric layer 21,the word lines 22 and the word line capping layer 23 in the trenches,but not limited thereto. In some embodiments, the word line dielectriclayer 21 may include silicon oxide or other suitable dielectricmaterials, the word lines 22 may include aluminum (Al), tungsten (W),copper (Cu), titanium aluminide (TiAl) or other suitable conductivematerials, and the word line capping layer 23 may include siliconnitride, silicon oxynitride, silicon carbon nitride (SiCN) or othersuitable insulation materials.

Next, as shown in FIG. 1 and FIG. 2, at least one bit line structure BLis formed on the semiconductor substrate 10. The bit line structure BLincludes a first metal layer 43A, a bit line capping layer 45A and afirst silicon layer 44A. The bit line capping layer 45A is disposed onthe first metal layer 43A, and the first silicon layer 44A is disposedbetween the first metal layer 43A and the bit line capping layer 45A ina perpendicular direction Z perpendicular to the semiconductor substrate10. The method of forming the bit line structure BL in this embodimentcan include but not limited to the following steps. First, as shown inFIG. 1, a multilayer stack structure 40 is formed on the semiconductorsubstrate 10, and the multilayer stack structure 40 includes a metallayer 43, a silicon layer 44 and a capping layer 45. The silicon layer44 is formed on the metal layer 43, and the capping layer 45 is formedon the silicon layer 44. The metal layer 43 may include aluminum,tungsten, copper, titanium aluminide or other suitable conductivematerial with low resistance. The silicon layer 44 may includepolysilicon, amorphous silicon or other suitable silicon containingconductive materials. The capping layer 45 may include silicon nitride,silicon oxynitride, silicon carbon nitride or other suitable insulationmaterials. Next, as shown in FIG. 2, a patterning process 90 isperformed to the multilayer stack structure 40 for forming the bit linestructure BL. Specifically, the first metal layer 43A in the bit linestructure BL can be formed by performing the patterning process 90 tothe metal layer 43 in the multilayer stack structure 40, the firstsilicon layer 44A can be formed by performing the patterning process 90to the silicon layer 44 in the multilayer stack structure 40, and thebit line capping layer 45A can be formed by performing the patterningprocess 90 to the capping layer 45 in the multilayer stack structure 40.In addition, an insulating layer 31 can be formed on the semiconductorsubstrate 10 before forming the multilayer stack structure 40 to coverthe word line capping layers 23, the shallow trench isolation 11 and theactive regions 13. An active region opening 33 can be formed topenetrate the insulating layer 31 and expose a portion of thecorresponding active region 13. The multilayer stack structure 40 may beformed on the insulating layer 31 and in the active region opening 33,so that the bit line structure BL formed subsequently can contact andelectrically connect to the corresponding active region 13.

Additionally, the multilayer stack structure 40 can be formed in thememory cell region R1 and the peripheral region R2, and the bit linestructure BL is at least partially formed in the memory cell region R1.Furthermore, the manufacturing method of this embodiment may furtherinclude forming at least one gate structure GS in the peripheral regionR2. The gate structure GS can be used to form a transistor in theperipheral region R2, and this transistor may include a transistor thatcan control the signal transmitting of the word lines 22 and/or the bitline structure BL, but not limited thereto. In some embodiments, thegate structure GS and the bit line structure BL can be formed togetherby performing the patterning process 90 to the multilayer stackstructure 40, so as to achieve the effects of process simplification andprocess integration, but not limited thereto. In some embodiments ofthis invention, the gate structure disposed in the peripheral region R2may also be formed by different processes and/or different materialsaccording to other considerations. When the gate structure GS is formedby performing the patterning process 90 to the multilayer stackstructure 40, the gate structure GS can include a second metal layer43B, a second silicon layer 44B and a gate capping layer 45B. The gatecapping layer 45B is disposed on the second metal layer 43B, and thesecond silicon layer 44B is disposed between the second metal layer 43Band the gate capping layer 45B in the perpendicular direction Z.

The second metal layer 43B, the second silicon layer 44B, and the gatecapping layer 45B can be formed by performing the patterning process 90to the metal layer 43, the silicon layer 44, and capping layer 45 in themultilayer stack structure 40 respectively. In addition, the multilayerstack structure 40 can further include a non-metallic conductive layer41 and a barrier layer 42, the non-metallic conductive layer 41 isdisposed between the metal layer 43 and the semiconductor substrate 10,and the barrier layer 42 is disposed between the non-metallic conductivelayer 41 and the metal layer 43, but not limited thereto. In someembodiments of this invention, the abovementioned non-metallicconductive layer 41 and barrier layer 42 may not be disposed in themultilayer stack structure 40 according to other considerations. Thenon-metallic conductive layer 41 may include polysilicon, amorphoussilicon or other non-metallic conductive materials that may containsilicon or not. The barrier layer 42 may include titanium, tungstensilicide (WSi), tungsten nitride (WN) or other suitable barriermaterials.

When the bit line structure BL and the gate structure GS are formed byperforming the patterning process 90 to the multilayer stack structure40, the bit line structure BL can further include a first non-metallicconductive layer 41A and a first barrier layer 42A, and the gatestructure GS can further include a second non-metallic conductive layer41B and a second barrier layer 42B. The first non-metallic conductivelayer 41A and the second non-metallic conductive layer 41B are formed byperforming the patterning process 90 to the non-metallic conductivelayer 41, and the first barrier layer 42A and the second barrier layer42B are formed by performing the patterning process 90 to the barrierlayer 42. Therefore, the first non-metallic conductive layer 41A isdisposed between the first metal layer 43A and the semiconductorsubstrate 10, the second non-metallic conductive layer 41B is disposedbetween the second metal layer 43B and the semiconductor substrate 10,the first barrier layer 42A is disposed between the first non-metallicconductive layer 41A and the first metal layer 43A, and the secondbarrier layer 42B is disposed between the second non-metallic conductivelayer 41B and the second metal layer 43B. Additionally, a gatedielectric layer 32 can be formed between the gate structure GS and thesemiconductor substrate 10 for being used as the gate dielectric layerin the transistor corresponding to the gate structure GS.

Next, as shown in FIG. 3, a spacer 51 can be formed on a sidewall of thegate structure GS in the peripheral region R2, the spacer 51 can be usedfor forming source/drain regions 52 in the semiconductor substrate 10 attwo sides of the gate structure GS, and a dielectric layer 53 is formednext to cover the source/drain regions 52, but not limited thereto. Inaddition, as shown in FIG. 3 and FIG. 4, the manufacturing method ofthis embodiment may further include forming at least one storage nodecontact 62 on the semiconductor substrate 10 and in the memory cellregion R1, and the storage node contact 62 is formed corresponding toand electrically connected to at least one of the active regions 13. Thestorage node contact 62 may be formed by forming an isolation structure61 with a plurality of openings on the semiconductor substrate 10,filling the openings of the isolation structure 61 with a conductivematerial, and then performing an etching back process to the conductivematerial, so that a top surface of the storage node contact 62 is lowerthan a top surface of the isolation structure 61 in the perpendiculardirection Z, and the top surface of the storage node contact 62 ishigher than a top surface of the semiconductor substrate 10, but notlimited thereto. The storage node contact 62 may include silicon, suchas amorphous silicon, polysilicon or other silicon containing conductivematerial. However, in some embodiments, the storage node contact 62 mayalso be formed by other processes and/or materials according to otherconsiderations.

Next, as shown in FIG. 5, at least one bit line contact opening H1 isformed, and the bit line contact opening H1 penetrates the bit linecapping layer 45A and exposes a portion of the first silicon layer 44A.In addition, a gate contact opening H2 and two source/drain contactopenings H3 can be formed in the peripheral region R2. The gate contactopening H2 penetrates the gate capping layer 45B and exposes at least aportion of the second silicon layer 44B, and each source/drain contactopening H3 penetrates the dielectric layer 53 and exposes thecorresponding source/drain region 52. The abovementioned bit linecontact opening H1, gate contact opening H2, and source/drain contactopenings H3 can be formed by an etching process with the same patternedmask, so as to achieve the effect of process simplification, but notlimited thereto. In some embodiments, the bit line contact opening H1,the gate contact opening H2, and the source/drain contact openings H3may also be formed respectively by different patterned masks and/oretching processes.

Next, as shown in FIG. 6 to FIG. 9, a first metal silicide layer 71 isformed on the portion of the first silicon layer 44A exposed by the bitline contact opening H1. The method of forming the bit line structure BLin this embodiment can include but not limited to the following steps.As shown in FIG. 6 and FIG. 8, an auxiliary metal layer 70 is formed onthe semiconductor substrate 10 first. The auxiliary metal layer 70 is atleast partially formed on the portion of the first silicon layer 44Aexposed by the bit line contact opening H1. Then, a thermal treatment isperformed to form the first metal silicide layer 71 on the portion ofthe first silicon layer 44A exposed by the bit line contact opening H1,and the auxiliary metal layer 70 is removed after the first metalsilicide layer 71 is formed. In some embodiments, the auxiliary metallayer 70 may include cobalt (Co), nickel (Ni) or other suitable metalmaterials, and the first metal silicide layer 71 may includecobalt-silicide, nickel-silicide or other suitable metal silicide. Inaddition, the manufacturing method of this embodiment may furtherinclude forming a second metal silicide layer 72 on the portion of thesecond silicon layer 44B exposed by the gate contact opening H2. In someembodiments, a material of the second metal silicide layer 72 and amaterial of the first metal silicide layer 71 are the same, and thesecond metal silicide layer 72 and the first metal silicide layer 71 canbe formed together by the same process, so as to achieve the effect ofprocess simplification, but not limited thereto. For example, theauxiliary metal layer 70 can be partially formed on the portion of thesecond silicon layer 44B exposed by the gate contact opening H2, and thesecond metal silicide layer 72 can be formed on the second silicon layer44B by the thermal treatment. Additionally, in some embodiments, adifferent process may also be performed to form the second metalsilicide layer 72 that is different from the first metal silicide layer71 according to other considerations.

As shown in FIG. 6 to FIG. 9, the manufacturing method of thisembodiment can further include forming a third metal silicide layer 73on the storage node contact 62. In some embodiments, a material of thethird metal silicide layer 73 and a material of the first metal silicidelayer 71 can be the same, and the third metal silicide layer 73 and thefirst metal silicide layer 71 can be formed together by the sameprocess, so as to achieve the effect of process simplification, but notlimited thereto. For example, the auxiliary metal layer 70 can bepartially formed on the storage node contact 62, and the third metalsilicide layer 72 can be formed on the storage node contact 62 by thethermal treatment. However, in some embodiments, a different process mayalso be performed to form the third metal silicide layer 73 that isdifferent from the first metal silicide layer 71 according to otherconsiderations. In addition, the auxiliary metal layer 70 is removedafter the first metal silicide layer 71 and the third metal silicidelayer 73 are formed. It is noteworthy that the first metal layer 43A ofthe bit line structure BL is completely covered by the first siliconlayer 44A and/or the first metal silicide layer 71 in the perpendiculardirection Z when removing the auxiliary metal layer 70. Therefore, thefirst metal layer 43A is protected from being damaged by the process ofremoving the auxiliary metal layer 70. Additionally, the second metallayer 43B of the gate structure GS is completely covered by the secondsilicon layer 44A and/or the second metal silicide layer 72 in theperpendicular direction Z when removing auxiliary metal layer 70.Therefore, the second metal layer 43B can be protected from beingdamaged by the process of removing the auxiliary metal layer 70. Inaddition, since the main purpose of forming the silicon layer 44 isprotecting the metal layer 43 and forming the metal silicide layer, thethickness of the silicon layer 44 can be adjusted according to thesilicon consumption in the process of forming the metal silicide.Therefore, the thicknesses of the first silicon layer 44A and the secondsilicon layer 44B are preferably less than the thicknesses of the firstnon-metallic conductive layer 41A and the second non-metallic conductivelayer 41B, but not limited thereto.

In addition, the manufacturing method of this embodiment can furtherinclude forming a fourth metal silicide layer 74 on the source/drainregion 52 exposed by the source/drain contact opening H3. In someembodiments, a material of the fourth metal silicide layer 74 and amaterial of the second metal silicide layer 72 can be the same, and thefourth metal silicide layer 74, the first metal silicide layer 71, thesecond metal silicide layer 72, and the third metal silicide layer 73can be formed together by the same process, so as to achieve the effectof process simplification, but not limited thereto.

Next, as shown in FIG. 10 and FIG. 11, a bit line contact structure 81is formed in the bit line contact opening H1, and the bit line contactstructure 81 contacts the first metal silicide layer 71 for beingelectrically connected to the bit line structure BL. The bit linecontact structure 81 may include a conductive material with lowresistance, such as aluminum, tungsten, copper, titanium aluminide, orthe like. A barrier layer (not shown) may further be formed between thelow resistance conductive material and the first metal silicide layer71, and this barrier layer may include single layer or multilayerbarrier layer structure and may include titanium, titanium nitride (TiN)or other suitable barrier materials. In addition, the manufacturingmethod of this embodiment can further include forming a gate contactstructure 82 in the gate contact opening H2, forming a contact structure83 on the third metal silicide layer 73, and forming a source/draincontact structure 84 in the source/drain contact opening H3. The gatecontact structure 82 contacts the second metal silicide layer 72 forbeing electrically connected to the gate structure GS. The contactstructure 83 contacts the third metal silicide layer 73 for beingelectrically connected to the storage node contact 62. The source/draincontact structure 84 contacts the fourth metal silicide layer 74 forbeing electrically connected to the source/drain region 52. In someembodiments, the bit line contact structure 81, the gate contactstructure 82, the contact structure 83, and the source/drain contactstructure 84 can be the same material and/or can be formed by the sameprocess, so as to achieve the effect of process simplification, but notlimited thereto.

According to the abovementioned manufacturing method, a semiconductormemory device 100 shown in FIG. 10 and FIG. 11 can be formed. Thesemiconductor memory device 100 of this embodiment includes thesemiconductor substrate 10, at least one bit line structure BL, at leastone bit line contact opening H1, the first metal silicide layer 71, andthe bit line contact structure 81. The bit line structure BL is disposedon the semiconductor substrate 10, and the bit line structure BLincludes the first metal layer 43A, the bit line capping layer 45A, andthe first silicon layer 44A. The bit line capping layer 45A is disposedon the first metal layer 43A, and the first silicon layer 44A isdisposed between the first metal layer 43A and the bit line cappinglayer 45A. The bit line contact opening H1 penetrates the bit linecapping layer 45A, the first metal silicide layer 71 is disposed on thefirst silicon layer 44A corresponding to the bit line contact openingH1, and the bit line contact opening H1 exposes at least a portion ofthe first metal silicide layer 44A. The bit line contact structure 81 isdisposed in the bit line contact opening H1, and the bit line contactstructure 81 contacts the first metal silicide layer 71 for beingelectrically connected to the bit line structure BL. The bit linestructure BL is at least partially disposed in the memory cell regionR1, and the semiconductor memory device 100 further includes the gatestructure GS, at least one gate contact opening H2, the second metalsilicide layer 72, and the gate contact structure 82. The gate structureGS is disposed on the semiconductor substrate 10 and disposed in theperipheral region R2, the gate structure GS includes the second metallayer 43B, the second silicon layer 44B, and the gate capping layer 45B.The gate capping layer 45B is disposed on the second metal layer 43B,and the second silicon layer 44B is disposed between the second metallayer 43B and the gate capping layer 45B. The gate contact opening H2penetrates the gate capping layer 45B, the second metal silicide layer72 is disposed on the second silicon layer 44B corresponding to the gatecontact opening H2, and the gate contact opening H2 exposes at least aportion of the second metal silicide layer 72. The gate contactstructure 82 is disposed in the gate contact opening H2, and the gatecontact structure 82 contacts the second metal silicide layer 72 forbeing electrically connected to the gate structure GS.

In addition, as shown in FIG. 10 and FIG. 11, the semiconductor memorydevice 100 can further include at least one storage node contact 62, atleast one third metal silicide layer 73 and the contact structure 83.The storage node contact 62 is disposed on the semiconductor substrate10, and the storage node contact 62 is disposed corresponding to andelectrically connected to at least one of the active regions 13. Thethird metal silicide layer 73 is disposed on the storage node contact62, the contact structure 82 is disposed on the third metal silicidelayer 73, and the contact structure 82 contacts the third metal silicidelayer 73 for being electrically connected to the storage node contact62. The first silicon layer 44A is disposed between the first metallayer 43A and the bit line capping layer 45A in the bit line structureBL, and thereby the first silicon layer 44A can protect the first metallayer 43A from being damaged by the process of forming the third metalsilicide layer 73 on the storage node contact 62. Accordingly,advantages of improving the electrical performance and increasing theproduct yield of the semiconductor memory device 100 can be obtained.

To sum up the semiconductor memory device and the manufacturing methodthereof in this present invention, the first silicon layer is disposedon the first metal layer in the bit line structure, and the firstsilicon layer can be used to protect the first metal layer from beingdamaged by the process of forming the metal silicide layer on thestorage node contact. In addition, the gate structure disposed in theperipheral region and the bit line structure can be formed together byperforming the patterning process to the same multilayer stackstructure, so that the second silicon layer can also be disposed on thesecond metal layer in the gate structure for protecting the second metallayer from being damaged by the process of forming the metal silicidelayer on the storage node contact.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. A manufacturing method of a semiconductor memorydevice, comprising: providing a semiconductor substrate; forming atleast one bit line structure on the semiconductor substrate, the bitline structure comprising: a first metal layer; a bit line capping layerdisposed on the first metal layer; and a first silicon layer disposedbetween the first metal layer and the bit line capping layer; forming atleast one bit line contact opening penetrating the bit line cappinglayer and exposing at least a portion of the first silicon layer;forming a first metal silicide layer on the portion of the first siliconlayer exposed by the bit line contact opening; and forming a bit linecontact structure in the bit line contact opening, wherein the bit linecontact structure contacts the first metal silicide layer for beingelectrically connected to the bit line structure.
 2. The manufacturingmethod of the semiconductor memory device according to claim 1, whereinthe step of forming the bit line structure comprises: forming amultilayer stack structure on the semiconductor substrate, themultilayer stack structure comprising: a metal layer; a silicon layerformed on the metal layer; and a capping layer formed on the siliconlayer; and performing a patterning process to the multilayer stackstructure for forming the bit line structure.
 3. The manufacturingmethod of the semiconductor memory device according to claim 2, whereina memory cell region and a peripheral region are defined on thesemiconductor substrate, the multilayer stack structure is formed in thememory cell region and the peripheral region, and the bit line structureis at least partially formed in the memory cell region.
 4. Themanufacturing method of the semiconductor memory device according toclaim 3, further comprising: forming a gate structure in the peripheralregion, wherein the gate structure and the bit line structure are formedtogether by performing the patterning process to the multilayer stackstructure.
 5. The manufacturing method of the semiconductor memorydevice according to claim 4, wherein the gate structure comprises: asecond metal layer, wherein the second metal layer and the first metallayer are formed by performing the patterning process to the metallayer; a gate capping layer disposed on the second metal layer, whereinthe gate capping layer and the bit line capping layer are formed byperforming the patterning process to the capping layer; and a secondsilicon layer disposed between the second metal layer and the gatecapping layer, wherein the second silicon layer and the first siliconlayer are formed by performing the patterning process to the siliconlayer.
 6. The manufacturing method of the semiconductor memory deviceaccording to claim 5, further comprising: forming at least one gatecontact opening penetrating the gate capping layer and exposing at leasta portion of the second silicon layer; forming a second metal silicidelayer on the portion of the second silicon layer exposed by the gatecontact opening; and forming a gate contact structure in the gatecontact opening, wherein the gate contact structure contacts the secondmetal silicide layer for being electrically connected to the gatestructure.
 7. The manufacturing method of the semiconductor memorydevice according to claim 6, wherein the first metal silicide layer andthe second metal silicide layer are formed together by a same process.8. The manufacturing method of the semiconductor memory device accordingto claim 2, wherein the multilayer stack structure further comprises anon-metallic conductive layer disposed between the metal layer and thesemiconductor substrate.
 9. The manufacturing method of thesemiconductor memory device according to claim 8, wherein the multilayerstack structure further comprises a barrier layer disposed between themetal layer and the non-metallic conductive layer.
 10. The manufacturingmethod of the semiconductor memory device according to claim 1, furthercomprising: forming at least one storage node contact on thesemiconductor substrate, wherein the semiconductor substrate comprises aplurality of active regions, and the storage node contact is formedcorresponding to and electrically connected to at least one of theactive regions; forming a third metal silicide layer on the storage nodecontact; and forming a contact structure on the third metal silicidelayer, wherein the contact structure contacts the third metal silicidelayer for being electrically connected to the storage node contact. 11.The manufacturing method of the semiconductor memory device according toclaim 10, wherein the first metal silicide layer and the third metalsilicide layer are formed together by a same process.
 12. Themanufacturing method of the semiconductor memory device according toclaim 11, wherein the step of forming the first metal silicide layer andthe third metal silicide layer comprises: forming an auxiliary metallayer on the semiconductor substrate, wherein the auxiliary metal layeris partially formed on the storage node contact and partially formed onthe portion of the first silicon layer exposed by the bit line contactopening; and removing the auxiliary metal layer after the first metalsilicide layer and the third metal silicide layer are formed.
 13. Themanufacturing method of the semiconductor memory device according toclaim 12, wherein the first metal layer of the bit line structure iscompletely covered by the first silicon layer and/or the first metalsilicide layer in a perpendicular direction when removing the auxiliarymetal layer.